bun-development

bun-development is a skill for Claude Code, Codex from pass-agent/loomkin. It costs 35 tokens per session (3,829 once invoked), scanned A, original, MIT.

A guide for developing JavaScript and TypeScript projects with Bun, a runtime that includes tools for installing packages, bundling code, and running tests.

In plain words
What is it for?
Use it to initialize projects, install or update Bun, run TypeScript and JSX, bundle applications, test code, and handle migrations from Node.js.
Why use it?
It helps developers start Bun projects, move from Node.js, use Bun's built-in tools, and diagnose Bun-specific problems.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is bun build ./src/index.ts --outdir ./dist.

Good fit Use it to initialize projects, install or update Bun, run TypeScript and JSX, bundle applications, test code, and handle migrations from Node.js.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/pass-agent/loomkin
agentmods
npx agentmods add skills/pass-agent/loomkin/bun-development

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for bun-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/pass-agent/loomkin/bun-development/github.svg)](https://agentmods.dev/skills/pass-agent/loomkin/bun-development)
Your own site
<a href="https://agentmods.dev/skills/pass-agent/loomkin/bun-development"><img src="https://agentmods.dev/badge/skills/pass-agent/loomkin/bun-development/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for bun-development

Your own site · 80×15
<a href="https://agentmods.dev/skills/pass-agent/loomkin/bun-development"><img src="https://agentmods.dev/badge/skills/pass-agent/loomkin/bun-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 35 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,829 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. ✓ AI security review Sonnet 5 · 6 Sept 2026 📄 Read the review
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00035 $0.03829
Opus 5.5 $0.00014 $0.01532
Sonnet 5.5 $0.00007 $0.00766
Haiku 4.5 $0.00003 $0.00383

Measured 1mo ago against content hash d61877c390db, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

bun-development scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

4 near-identical copies found in the catalogue:

apps/cli/.agents/skills/bun-development/SKILL.md · 697 lines

How it starts

The opening of the file, as written. The whole thing — 697 lines — stays where its author put it; the contents beside it link to each section on GitHub.

⚡ Bun Development

Fast, modern JavaScript/TypeScript development with the Bun runtime, inspired by oven-sh/bun.

When to Use This Skill

Use this skill when:

  • Starting new JS/TS projects with Bun
  • Migrating from Node.js to Bun
  • Optimizing development speed
  • Using Bun's built-in tools (bundler, test runner)
  • Troubleshooting Bun-specific issues

1. Getting Started

1.1 Installation

# macOS / Linux
curl -fsSL https://bun.sh/install | bash

# Windows
powershell -c "irm bun.sh/install.ps1 | iex"

# Homebrew
brew tap oven-sh/bun
brew install bun

# npm (if needed)
npm install -g bun

# Upgrade
bun upgrade

1.2 Why Bun?

Feature Bun Node.js
Startup time ~25ms ~100ms+
Package install 10-100x faster Baseline
TypeScript Native Requires transpiler
JSX Native Requires transpiler
Test runner Built-in External (Jest, Vitest)
Bundler Built-in External (Webpack, esbuild)

2. Project Setup

2.1 Create New Project

# Initialize project
bun init

# Creates:
# ├── package.json
# ├── tsconfig.json
# ├── index.ts
# └── README.md

# With specific template
bun create <template> <project-name>

# Examples
bun create react my-app        # React app
bun create next my-app         # Next.js app
bun create vite my-app         # Vite app
bun create elysia my-api       # Elysia API

2.2 package.json

{
  "name": "my-bun-project",
  "version": "1.0.0",
  "module": "index.ts",
  "type": "module",
  "scripts": {
    "dev": "bun run --watch index.ts",
    "start": "bun run index.ts",
    "test": "bun test",
    "build": "bun build ./index.ts --outdir ./dist",
    "lint": "bunx eslint ."
  },
  "devDependencies": {
    "@types/bun": "latest"
  },
  "peerDependencies": {
    "typescript": "^5.0.0"
  }
}

Read the full file on GitHub · 697 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 697 lines · 35 tokens per session scan E d61877c390db

Subscribe to this mod's changes

bun-development is a skill published in the GitHub repository pass-agent/loomkin (181 stars, last pushed 5mo ago), licensed MIT. It adds 35 tokens to every session and 3,829 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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